[Tutor] Help with "Guess the number" script

[spir]

On 03/03/2014 05:03 AM, Scott W Dunning wrote:

Ben Finney makes numerous fine comments already. I'll add a few, some on the 
same points but but expressed a bit differently (case it helps).

> This is what Im having trouble with now.  Here are the directions I’m stuck on and what I have so far, I’ll bold the part that’s dealing with the instructions if anyone could help me figure out where I’m going wrong.
>
> Thanks!
>
> from random import randrange
> randrange(1, 101)
> from random import seed
> seed(129)
>
> def print_description():
>      print """Welcome to Guess the Number.
>      I have seleted a secret number in the range 1 ... 100.
>      You must guess the number within 10 tries.
>      I will tell you if you ar high or low, and
>      I will tell you if you are hot or cold.\n"""
>
> def get_guess(guess_number):
>      promt = "(" + str(guess_number) +") Please enter a guess:"
>      user_guess = raw_input(promt)
>      user_guess = int(user_guess)
>      return user_guess

Very good choice of variable name for 'promt'. (Apart from ortography, but since 
you are consistent with the error... ;-)

There are 2 user guesses here, and only 1 variable, thus 1 name. The name should 
say what (idea) the variable represents in the program; this should be said by 
the name's *meaning*. It is one of the greatest difficulties in programming. How 
would you define what these variables represent, using everyday language? My own 
definitions would lead me to choose the following variable names:
      guess_text   = raw_input(promt)
      guess_number = int(user_guess)
      return guess_number
Note: it is especially obviuos that these are 2 separate numbers, since they do 
not even are of the same type (a piece of text, or "string", vs a number, here 
an "int").

Good naming is very, very hard; differences of naming can make some piece of 
program nearly trivial or instead nearly impossible to understand; often bad 
naming is worse than hypothetical randomly chosen names, because bad naming 
*misleads* your thinking.

Changing the value of a local variable is always, or nearly, a sign that there 
are here 2 ideas which should be represented by 2 variables with 2 names. 
Example of 2 programming styles (note the difference in ease of understanding, 
even if you don't know the python features used here):

def get_data (data):
     data = File(data)		# (a file)
     data = data.read()		# (a piece of text)
     data = data.split("")	# (a list of words)
     return data
...
data = get_data("data.text")

def data_words (file_name):
     data_file = File(file_name)		# (a file)
     text = data_file.read()		# (a piece of text)
     words = text.split(" ")		# (a list of words)
     return words
...
words = data_words("data.text")

(A special case is loop variables, but even then you only write the assignment 
once, the value chages across multiple passes on the same code. The only real 
exception is accumulators, like for computing a sum, which need to be first 
initialised to a start value, often 0.)

> def print_hints(secrets, guess):
>      secret_number = secret
>      guess = guess
>      if guess < 0 or user_guess> 101:
>          print "Out of range!"

Parameters are input variables. Once they are given execution values by a call like
     print_hints(input_value1, input_value2)

these variables exist _inside_ the function body (each with a name and a value). 
As if functions were defined like:
     def print_hints:		# note: no param
         secret = input_value1
         guess  = input_value2
         ... use these variables ...
This is more or less what the language does for you. This is the whole point of 
defining parameters, in fact. So, _you_ do not need to _rebind_ parameters to 
local variables; they already are local variables.

In addition, you are not consistent with variable _names_, evendently, so your 
programs have no chance to work. This is an annoying, but necessary part of 
programming. But the language will always tell about such errors, at once, *if 
and only if* the wrong name does *not* otherwise exist. --> pay attention!

> def main():
>      print_description()
>      secret = randrange(1,101)
>      current_guess = get_guess(1)
>      if current_guess != secret:
>          print_hints(secret_number, guess)
>          current_guess = get_guess(2)

* 'secret_number' appears from nowhere: pay attention!
* To be more coherent checking if the guess is right or wrong (or too high or 
too low) should be done in function print_hints as well. This function 
_evaluates_ the guess (maybe it should be renamed).

>      if secret == current_guess:
>          print "Congratulations, you win!"
>      else:
>          print "Please play again"
>      print "The secret number was", secret

These are (also) hints to the player, actually, aren't they?

> main()

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